This invention relates to a cargo restraint and delivery system having a simultaneous control used for logistics and a sequential control used for combat off-loading and aerial delivery where, in the latter instance, a load-sensing mechanism including a spring fuse operates in the system for the delivery of cargo.
Cargo drops by parachute from an aircraft have been extensively employed in military operations and disaster relief situations. In the usual parachute cargo delivery system, pallets loaded with cargo are guided for movement along the longitudinal axis of the aircraft between parallel rails secured to the aircraft floor. The force developed by a deployed parachute is used to pull the cargo backwardly out of the rear cargo-receiving and delivery opening in the aircraft. Desirably, the aircraft must also be capable of discharging cargo onto the ground while the aircraft accelerates over the ground surface.
In the prior art cargo delivery systems, one of the two restraint rails used to guide the cargo pallets is provided with aerial delivery locks that permit only aft movement of a pallet under the force exerted by a parachute. Logistic locks are carried on the other rail to prevent both forward and aft movements of the cargo during normal flight conditions. In the aerial delivery mode of operation, the logistic locks on one rail are all disengaged while the aerial delivery locks on the other rail provide all forward and aft restraints for the cargo. If it is necessary to return to a logistically-locked status, then manual reengagement of the logistic locks must be undertaken. This reengagement of the logistic lock may be very difficult due to a misalignment between slots in the cargo pallets and the logistic locks should the pallets shift slightly. Furthermore, prior art systems wherein locks are used on both rails are heavy, complex and generally unreliable.
One form of aerial delivery system intended to overcome these disadvantages is disclosed in U.S. application Ser. No. 92,146, now U.S. Pat. No. 4,241,890 issued Dec. 30, 1980 assigned to the assignee of this invention. In this aerial delivery system, all of the pallet locks are carried on one guide rail and controlled by a single control rod extending to a loadmaster station. The function of the pallet locks is combined for both the aerial delivery system and logistics. Each lock for a pallet never has to disengage from the load unless the cargo is actually unloaded. A bending fuse is used to restrain a pallet in its proper position until a minimum predetermined load is applied to the pallet by an extended parachute. At this moment, the fuse fails in bending, allowing the pallet to be dragged out of the rear cargo-delivery opening by the parachute. The failure point of the fuse is chosen by a selected characteristic of the metal used to fabricate the fuse to vary tolerances of the fuse. However, unnecessary logistics are required to provide aircraft with fuses which are especially undesirable during warfare. The replacement of a set of ruptured fuses after an aerial cargo delivery operation requires time and expense that are eliminated by the system of the present invention. Moreover, on present military aircraft, cargo-restraining rails and operating mechanism therefor are installed and removed from the aircraft as utilization requires. Recent requirements for cargo handling provide that cargo restraint rails and operating mechanism therefor are to be a permanent part of the aircraft rather than a kit which is used only when needed. The space available on recent aircraft, such as the C14, is not sufficient to use the arrangement of cargo rails with cargo restraint locks presently used on aircraft.